High-strength split one-piece machined 2-gear 13/17T pinion gear module from tough 7075 T6 aluminum and specially hard coated for superior energy, light-weight, and high durability. Developed on an exceptional gear item, all pinions work ultra-precise enamel shaping and ultra-true working for vibration-free procedure. Fine inside threading allows easy installation. Each pinion is fine etched due to the enamel quantity for quick & effortless recognition.